Manufacturing of diffractive pigments by fluidized bed chemical vapor deposition

Abstract

Microstructured pigments include a dielectric core having a diffraction grating. The microstructured dielectric core is encapsulated with one or more encapsulation layers which are deposited using chemical vapor deposition in a fluidized bed. The fluidizing conditions allow for providing uniform and highly-conforming encapsulation layers.

I claim: 
     
       1. A method of forming a microstructured pigment flake comprising:
 depositing a single dielectric layer on a microstructured substrate to form a single microstructured dielectric layer; 
 separating the single microstructured dielectric layer from the microstructured substrate; 
 breaking only the single microstructured dielectric layer to form a plurality of microstructured dielectric cores; 
 encapsulating the microstructured dielectric cores with one or more additional dielectric layers by chemical vapor deposition in a fluidized bed, 
 wherein the microstructured pigment flake exhibits a diffractive effect provided by a grating in at least one of a surface of the microstructured dielectric core, and one or more additional dielectric layers. 
 
     
     
       2. The method as defined in  claim 1 , wherein the chemical vapor deposition includes a thermally activated reaction. 
     
     
       3. The method as defined in  claim 1 , wherein the chemical vapor deposition comprises plasma activation. 
     
     
       4. The method as defined in  claim 1 , wherein encapsulating the plurality of microstructured dielectric cores includes providing a fluidizing gas through the bottom of the fluidized bed. 
     
     
       5. The method as defined in  claim 1 , wherein encapsulating the plurality of microstructured dielectric cores includes providing a precursor to the fluidized bed from above. 
     
     
       6. The method as defined in  claim 1 , wherein encapsulating the plurality of microstructured dielectric cores includes providing a precursor through the bottom of the fluidized bed. 
     
     
       7. The method as defined in  claim 1 , wherein encapsulating the plurality of microstructured dielectric cores includes providing a reactant in a direction opposite to a flow of a precursor. 
     
     
       8. The method as defined in  claim 1 , wherein the chemical vapor deposition includes using an organometallic precursor. 
     
     
       9. The method as defined in  claim 1 , wherein the fluidized bed includes a porous or perforated bottom plate. 
     
     
       10. The method as defined in  claim 1 , wherein each of the plurality of microstructured dielectric cores comprises the grating in the surface thereof. 
     
     
       11. The method as defined in  claim 10 , wherein each of the one or more additional dielectric layers conforms to the grating in the surface of each of the plurality of microstructured dielectric cores. 
     
     
       12. The method as defined in  claim 10 , wherein each of the one or more additional dielectric layers replicates the grating in the surface of each of the plurality of microstructured dielectric cores. 
     
     
       13. The method as defined in  claim 1 , wherein the microstructured dielectric core is formed of a low refractive index material. 
     
     
       14. The method as defined in  claim 1 , wherein the one or more additional dielectric layers are formed of a high refractive index material. 
     
     
       15. A method of forming a microstructured pigment flake comprising:
 depositing only a single dielectric layer directly onto a microstructured surface to form a single microstructured dielectric layer; 
 separating the single microstructured dielectric layer from the microstructured surface; 
 breaking the single microstructured dielectric layer to form a plurality of microstructured dielectric cores; 
 encapsulating the microstructured dielectric cores by chemical vapor deposition in a fluidized bed, 
 wherein the microstructured pigment flake exhibits a diffractive effect provided by a grating in a surface of the microstructured dielectric layer.